Question: Why does maple compute $\prod_{k=3}^{\infty} \cos \left(\frac{\pi}{k}\right)$ as $0$?

February 25 2014 ali_shakiba 10
Maple
1

I have computed the infinite multiplication using Maple, $\Pi_{k=3}^{\infty} ( \cos (\frac{\pi}{k} ))$, as follows, but it resulted in 0! I wonder why this happened, although maple was using exact arithmetic.


    P := Product(cos(Pi/k), k = 3 .. infinity)   

    value(P)

Note that if I use floating-point instead, it gives me the right answer, 0.1149420449.


    evalf(P)
By the way, I did not expect such a situation! Exact arithmetic should be exact! I am multiplying non-zero numbers to each other, starting from $1/2$ to $1$ as $n \rightarrow \infty$. So it should not be zero! Why such a thing happened?

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